US10735288B2 - Component for a machine or industrial plant and method for controlling a component in a machine or industrial plant - Google Patents
Component for a machine or industrial plant and method for controlling a component in a machine or industrial plant Download PDFInfo
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- US10735288B2 US10735288B2 US16/115,707 US201816115707A US10735288B2 US 10735288 B2 US10735288 B2 US 10735288B2 US 201816115707 A US201816115707 A US 201816115707A US 10735288 B2 US10735288 B2 US 10735288B2
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- H04L43/00—Arrangements for monitoring or testing data switching networks
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/418—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM]
- G05B19/4185—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM] characterised by the network communication
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- H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
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- H04L67/125—Protocols specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks involving control of end-device applications over a network
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Definitions
- the present disclosure relates to a component for a machine or industrial plant and a method for controlling a component in a machine or industrial plant, in both of which in the case of a data transfer between the components of the industrial plant without data packet repetition successive data packet errors are avoided, so that a secure, real-time-enabled data transfer is possible.
- control devices are used for example for controlling transport systems, for controlling tools, such as welding tools, screwing and/or drilling tools, riveting tools, etc., for controlling sensors, controlling actuators, such as linear motors and rotary machines, etc.
- tools such as welding tools, screwing and/or drilling tools, riveting tools, etc.
- sensors controlling actuators, such as linear motors and rotary machines, etc.
- actuators such as linear motors and rotary machines, etc.
- part 9 Processing sequences
- DIN ISO/IEC 2382 the real-time operation of a computing system is understood to mean one in which programs for processing incoming data are constantly operationally ready, such that the processing results are available within a specified time interval.
- the data can accrue according to a temporally random distribution or at predetermined times.
- time-critical data packets In real-time capable networks, the transmission of time-critical data packets must be guaranteed within a specific time frame. In many real-time systems, this time window is defined by communication cycles, in which data are exchanged periodically or cyclically.
- control and status data are continuously exchanged between a central control device and a plurality of sensors or actuators.
- the important criteria are real-time capability with guaranteed maximum transmission times and a high reliability of the data.
- the data transmission procedure must ensure that data are successfully delivered at a particular time.
- the rest of the transmission capacity can be used, among other things, for a transmission of additional, non-time-critical data to the same network node and/or a transmission of time-critical and non-time-critical data to other network nodes in the same transmission medium and/or transmission pauses to reduce the energy consumption.
- the time frame and the allocation of the transmission capacity are usually performed by a central controller.
- the object of the present disclosure is to provide a component for a machine or industrial plant and a method for controlling a component in a machine or industrial plant, with which the above problems can be solved.
- a component for a machine or industrial plant and a method for controlling a component in a machine or industrial plant will be provided, with which failures of components of the industrial plant can be minimized.
- the controller comprises a network communication device for controlling a transmission of data in a data network of the machine or industrial plant, in which data packets with a predetermined packet length are transmitted cyclically between the component and at least one other component of the machine or the industrial plant without a repeat transmission of time-critical data of the data packet being possible in a transmission cycle, wherein the network communication device is designed to tolerate a possible packet error in a received data packet, which was sent in the preceding transmission cycle, and to signal to the at least one additional component in the following transmission cycle a presence or absence of a packet error, wherein the network communication device is configured to determine whether or not the at least one other component has signaled a packet error for a data packet sent by the component in the previous transmission cycle, wherein the network communication device is designed, depending on the determined result, to adjust the number of redundancy data items in the data packet to be sent in the following transmission cycle, which will increase a correction probability of bit errors in the time-critical
- very short data transmission cycle times are possible, since no retransmissions are necessary.
- very short data transmission cycle times of this kind are less than or equal to 1 ms.
- the component offers a high energy efficiency, since the additional redundancy must only be transmitted and evaluated in rare cases.
- the described component implements an efficient prevention of critical multiple errors, which in certain applications, e.g. in the area of industrial communication in the industrial plant, represent the crucial quality characteristic.
- the component is also applicable in future, real-time enabled networks with short cycle times that use a faulty transmission medium with an increased bit error probability, such as a radio transmission, unshielded cables, etc., and in which a repeated transmission in a cycle is not possible and therefore is not an option for handling packet transmission errors.
- a faulty transmission medium with an increased bit error probability such as a radio transmission, unshielded cables, etc.
- the network communications device may be configured, if no packet error is determined in the preceding transmission cycle, to increase the number of time-critical data in the data packet to be transmitted in the following transmission cycle or to include non-time-critical data, which are indeed to be transferred but for which a time delay is non-critical, and wherein the network communication device is designed, if a packet error is determined in the preceding transmission cycle, to include the redundancy data in the data packet to be sent in the following transmission cycle instead of the non-time-critical data or a portion of the time-critical data.
- the network communication device is also configured to include in the data packet: a first piece of information concerning whether a data packet, which in the preceding cycle was sent to the component by the at least one additional component, had a packet error or not, and a second piece of information concerning the current configuration of the data packet to be sent in the current transmission cycle, wherein the second information item can be used by the at least one other component for an error correction of the time-critical data.
- the first information can be contained in one bit, and the second piece of information can specify the number of check bits in the data packet.
- the redundancy data items are check bits.
- the network communication device is additionally designed to examine the time-critical data for bit errors and if at least one bit error is present to perform an error correction of the time-critical data on the basis of the second piece of information and the redundancy data.
- the component also has an application which is designed to use the time-critical data, wherein the network communication device is also designed to transfer the time-critical data to the application if the network communication device has not detected a packet error, and wherein the network communication device is further designed to communicate to the application that transmission errors have occurred and no valid data are available in this transmission cycle if the network communication device has detected a packet error.
- the component is a control device, which is designed to control at least one tool of the industrial plant as the at least one other component.
- the component is a control device of a machine, wherein the control device is designed to control at least one sensor and/or actuator as the at least one other component, or wherein the component is a control device of a vehicle, wherein the control device is designed to control a power-assisted steering or servo-assisted braking system of the vehicle.
- At least two of the previously described components can be part of a data network, which also has a cable-bound or wireless transmission medium, wherein the at least two components are connected to each other via the transmission medium, to be able to perform a transmission of data in the data network, in which data packets with a predetermined packet length are transmitted cyclically between one of the components and at least one other component of the machine or industrial plant without a repeat transmission of time-critical data of the data packet being possible in a transmission cycle.
- a control device may be designed to control at least one tool of the industrial plant as the other component and/or designed to control at least one sensor and/or actuator as the additional component, wherein the control device is designed in such a way that the control unit as the central controller can bi-directionally exchange data packets with each additional component, and wherein each additional component is designed in such a way that each of the other components can only exchange data packets with the central controller.
- the object is also achieved by a method for controlling at least one component in a machine or industrial plant according to one embodiment.
- a network communication device is provided for controlling a transmission of data in a data network of the machine or industrial plant, in which data packets with a predetermined packet length are transmitted cyclically between the component and at least one other component of the machine or the industrial plant without a repeat transmission of time-critical data of the data packet being possible in a transmission cycle.
- the method comprises the steps: tolerating, with the network communication device, a possible packet error in a received data packet which was sent in the preceding transmission cycle, determining with the network communication device whether or not the at least one other component has signaled a packet error for a data packet transmitted by the component in the preceding transmission cycle, adjusting using the network communication device, depending on the determined result, the number of redundancy data items in the data packet to be sent in the following transmission cycle, which will increase a correction probability of bit errors in the time-critical data to be sent, and including signaling data in the data packet to be sent, which signal to the at least one other component a presence or absence of a packet error in the following transmission cycle.
- FIG. 1 shows a highly simplified view of an industrial plant, in which components of the industrial plant according to the first exemplary embodiment are connected in a data network for performing data transmission;
- FIG. 2 shows a simplified structure of an encoded data packet with weak channel coding according to the first exemplary embodiment
- FIG. 3 shows a highly simplified structure of an encoded data packet with strong channel coding according to the first exemplary embodiment
- FIG. 4 to FIG. 6 show diagrams each illustrating a method for controlling a component in an industrial plant according to the first exemplary embodiment.
- FIG. 1 shows an industrial plant 1 , which can be, for example, a production line for vehicles, furniture, building structures, etc., or a chemical plant etc., in which media or workpieces 4 , 5 are transported and/or can be processed with at least one tool, such as with an agitator, a welding tool, a screwdriver and/or drill, a stamping tool, a riveting tool, etc.
- the machine is optionally a vehicle, which has a controller for a power steering system or servo-assisted braking system or for other components of the vehicle. Any number of other examples of a machine and/or industrial plant 1 are conceivable.
- the industrial plant 1 has a control device 10 as a component of the machine or industrial plant 1 , a transmission medium 20 and at least one additional component 31 , 32 , 33 .
- the control device 10 and the at least one additional component 31 , 32 , 33 of the machine or industrial plant 1 use the transmission medium 20 jointly and form a data network.
- Both the control device 10 and the at least one other component 31 , 32 , 33 can each bi-directionally exchange data in the form of data packets 21 , 210 via the transmission medium 20 for applications 101 , 311 to 31 N, 321 , 331 to 33 N.
- the control device 10 has a network communication device 100 .
- the control device 10 as an application 101 has, for example, a microcontroller, a storage device, and software, etc.
- the software implements, for example, a comparison device that compares actual variables in the operation of the industrial plant 1 with target values.
- an evaluation device can be implemented, which on the basis of the output of the comparison device produces new control data, which are to be transferred in the data packets 21 , 210 in real time or non-real time over the transmission medium 20 to the at least one additional component 31 , 32 , 33 .
- the real-time control data are then generally referred to as time-critical data.
- the non-real-time control data are generally referred to as non-time-critical data.
- the first additional component 31 is, for example, a device which as at least one application 311 to 31 N has at least one element to be controlled, in particular at least one actuator or drive unit.
- the at least one actuator or drive unit can drive an axle into a rotary motion or alternatively into a linear motion.
- the first additional component 31 can be a robot, a transport device, a rotary machine, a screw tool, an agitator, etc.
- the control of the first additional component 31 and/or its at least one application 311 to 31 N is performed at least partly on the basis of the control data of the control device 10 , which the first additional component 31 receives in the data packets 21 , 210 .
- the second additional component 32 is, for example, an operating device, which is to be controlled in relation to which displays are displayed by it, or which is controlled by inputs from a user, for example.
- the operating device has, for example, a keyboard and/or a mouse and/or a touch-sensitive or non-touch-sensitive display screen etc., or combinations thereof.
- the operating device is a control panel, a personal computer, a laptop, a smartphone, tablet PC, etc.
- the control of the second additional component 32 and/or its at least one application 321 is performed at least partly on the basis of the control data of the control device 10 , which receives the second additional component 32 in the data packets 21 , 210 .
- the third additional component 33 is, for example, a sensing device, which has at least one sensor as application 331 to 33 N.
- the at least one sensor can detect actual values of physical or chemical properties of the workpieces 5 , 6 or dimensions or distances of tools from the workpieces 5 , 6 , etc., according to requirements. Arbitrary types of actual values are conceivable.
- the control of the third additional component 33 and/or its at least one application 331 to 33 N is performed at least partly on the basis of the control data of the control device 10 , which the first additional component 33 receives in the data packets 21 , 210 .
- the additional components 31 , 32 , 33 each transmit data packets 21 or data packets 210 to the control device 10 as a component of the industrial plant 1 .
- the data packets 21 , 210 contain, for example, results of the control processes, produced in the additional components 31 , 32 , 33 based on the control data of the control device 10 .
- Each data packet 21 , 210 corresponds to one of at least two channel codings of the transmission medium 20 .
- the at least two channel codings each lead to the same encoded packet length, as shown in FIG. 2 and FIG. 3 .
- FIG. 2 shows the structure of a data packet 21 in more detail.
- the data packet 21 has four different sections, which are ordered sequentially in time in a predetermined packet length N.
- the predetermined packet length N corresponds to a number of bits N.
- the data packet 21 has a first section for signaling data 211 , a second section for time-critical data 212 , a third section for non-time-critical data 213 and a fourth section for first redundancy data 214 .
- the first and second section together have a number of bits LL
- the non-time-critical data items 213 have a number of bits L2. Therefore, the first redundancy data items 214 have a number of bits N-L1-L2.
- the signaling data 211 contain pieces of information 211 A, 211 B as to whether the preceding transmission was successful or not, and pieces of information which specify the current configuration of the error correction, for example the number of check bits, as will be more accurately described and explained in reference to FIG. 4 to FIG. 6 .
- a data packet 210 in the case of a data packet 210 by contrast, only three different sections are present, which are also are arranged sequentially in time in the predetermined packet length N.
- the predetermined packet length N corresponds to the number of bits N.
- the data packet 210 also has the first section for signaling data 211 and the second section for time-critical data 212 .
- the data packet 210 has a third section for second redundancy data 215 .
- the first and second section together have the number of bits L1. Therefore, the second redundancy data items 215 have a number of bits N-L1.
- the data packet 21 according to FIG. 2 corresponds to a weaker channel coding than the data packet 210 according to FIG. 3 .
- the parameters of the channel coding are chosen in such a way that the number of user bits in the stronger channel coding for the data packet 210 is at least equal to the length of the time-critical data 212 .
- the length of the time-critical data 212 is derived from the number of bits for the time-critical data 212 .
- the moderate channel coding in accordance with the data packet 21 is chosen in such a way that, for the expected bit error probability of the transmission over the transmission medium 20 , in most cases all transmission errors can be eliminated.
- the packet error probability PER 1 does not yet necessarily correspond to the desired error probability of system-critical multiple errors.
- the stronger channel coding in accordance with the data packet 21 is chosen in such a way that, despite the higher number of redundant bits, the same coded predefined packet length N is used as in the moderate or weaker channel coding. Therefore, the number of user bits is reduced. This can be achieved in one case by the transmission of non-time-critical data 213 being temporarily suspended. Alternatively or additionally, the transmission of time-critical data 212 that can be omitted at the present time can be suspended, in the hope that they will be transmitted correctly again in the next cycle.
- the parameters of the stronger channel coding are chosen in such a way that the probability of error after the decoding is less than the target probability of the critical multiple errors.
- the probability of single packet errors is PER 1 . If such a single error is detected by the control device 10 or one of the components 31 , 32 , 33 , the stronger channel coding is applied in the next cycle, i.e. a data packet 210 is used. The conditional probability that a first error occurs and a new error then occurs is PER 2 . The probability of double errors is thus PER 1 ⁇ PER 2 .
- the communication is described which takes place in the operation of the industrial plant 1 between the control device 10 as a component of the industrial plant 1 and the other components 31 , 32 , 33 .
- a method for controlling a component 10 , 31 , 32 , 33 in the machine or industrial plant 1 is carried out.
- the method can be integrated into any suitable transmission methods, such as Sercos III, EtherCAT, Profinet, etc.
- a transmission cycle K has a duration T_K.
- a transmission cycle K+1 which directly follows the transmission cycle K, has a duration T_K+1.
- the transmission capacity which is provided as an example of the periodic or cyclic communication between the control device 10 and the other component 31 in the transmission cycles K and K+1, is represented in FIG. 4 by the rectangles for the packets 21 A.
- packets 21 B, 210 A are also transmitted, as will be explained below.
- the data to be transmitted i.e. time-critical and non-time-critical data 212 , 213
- the MAC layer 1001 , 3101 controls how the data packets 21 A, 21 B, 210 A are assembled depending on the system status.
- the system status is oriented, for example, according to which tasks are to be performed in the machine or industrial plant 1 .
- the respective data packets 21 A, 21 B, 210 A are then transferred to a channel coding/decoding layer 1002 , 3102 , where depending on the setting, a weak or strong redundancy is added. This results in the different type of channel coding 200 shown for the data packets 21 A, 21 B, 210 A in FIG. 2 and FIG. 3 .
- a data packet 21 A contains time-critical and non-time-critical data 212 , 213 and redundancy data 214 and in the signaling data 211 a signal 211 A, that the data of a data packet of the preceding transmission cycle were error-free.
- a data packet 21 B is structured in the same way as a data packet 21 A, except that in the signaling data 211 a signal 211 B shows that the data of a data packet of the preceding transmission cycle were not error-free, and therefore a packet error 26 ( FIG. 5 and FIG. 6 ) was present.
- a data packet 210 A contains time-critical data 212 and redundancy data 214 , and in the signaling data 211 a signal 211 A that the data of a data packet of the preceding transmission cycle were error-free.
- the coded data packets 21 A, 21 B, 210 A are then transmitted in the transmission medium 20 , wherein only the reserved transmission resource, in particular a specific time slot, can be used. If the fault 25 occurs in the transmission medium 20 , bit errors can occur in the data packets 21 A, 21 B, 210 A during the transmission via the faulty medium 20 .
- the respective data packet 21 A, 21 B, 210 A is received and decoded. In most cases any bit errors can be eliminated by the error correction. If this is not possible, transmission errors should at least be reliably detected.
- Known methods are suitable for this, such as cyclic redundancy check (CRC).
- the information as to whether the transfer was successful is communicated firstly to the MAC layer 1001 , 3101 of the network node or the control device 10 or one of the components 31 , 32 , 33 .
- the MAC layer 1001 , 3101 then forwards the received user data, namely the time-critical and/or non-time-critical data 212 , 213 , to the application layer 1001 , 3101 or discards erroneous data.
- the network node or control device 10 or one of the components 31 , 32 , 33 transmits the success or failure of the channel decoding by means of the layer 1002 , 3102 together with its user data in the reverse direction.
- the basic procedure in this case consisting of assignment of the packet structure, channel coding, transmission with the assigned resource and decoding at the receiver, is identical to the forward direction.
- the bi-directional communication in the transmission medium 20 can be implemented, as shown in FIG. 4 to FIG. 6 , as a half-duplex procedure, in which transmission can only take place in one direction at any given time.
- the bidirectional communication in the transmission medium 20 can be implemented as a full-duplex procedure, in which it is possible to transmit in both directions at the same time.
- the rest of the transmission capacity which is obtained due to the free time frames between the reserved frames, could be used for additional transmission services or other network nodes.
- FIG. 4 shows a transmission without packet errors for the transmission cycles K and K+1. Therefore, only the weaker channel coding is used in both transmission directions. As a result, data packets 21 A are sent in each case.
- the successful error correction is communicated to the MAC layer 1002 , 3102 as message 216 A and to the transmitter by the ACK signal 211 A. As long as the control device 10 or the component 31 receives an ACK as the signal 211 A, the weak channel coding is used for the following cycle.
- a packet error 26 occurs in the forward direction in the transmission cycle K. If such a packet error 26 cannot be corrected in the cycle K during the channel decoding in the network node such as the component 31 , but can be detected, then this will be communicated to the MAC layer 1002 , 3102 as message 216 B. The MAC layer 3102 then discards the received user data 212 , 213 . The packet error 26 is communicated to the application layer, which then responds accordingly. In the case of the non-time-critical data 213 a transmission retry may be requested. It is assumed that in spite of the packet error 26 the ACK signal 211 A is always received correctly and it is known to the receiver which channel coding 200 was applied in each case.
- time-critical data 212 and non-time-critical data 213 are transmitted in the reverse direction as usual and protected with the weaker channel coding. It is now signaled to the control device 10 with the NACK signal 211 B that a packet error 26 has occurred in the forward direction. Therefore, the data packet sent by the component 31 to the control device 10 is now a data packet 21 B.
- control device 10 receives the data packet 21 B with the NACK signal 211 B, in the following cycle K+1 it briefly interrupts the transmission of non-time-critical data 213 , and instead uses the stronger channel coding for the next transmission in the forward direction. For the resulting data packet 210 A with the ACK signal 211 A, new packet errors 26 in the time-critical data 210 A are then highly unlikely.
- FIG. 6 shows an example in which a packet error 26 occurs in the transmission cycle K in the reverse direction.
- the procedure here is equivalent to packet errors 26 in the forward direction.
- the packet error 26 is detected in the control device 10 . Therefore, the data error 26 is communicated to the component 31 by the NACK signal 211 B with the next data packet 21 B in the forward direction in the cycle K+1.
- the component 31 in the cycle K+1 then interrupts the transmission of non-time-critical data 213 and instead increases the redundancy, so that a data packet 210 A is transmitted.
- the adaptive channel coding 200 in the present method does not relate to an errorful data packet itself, but to the data packet following the errorful data packet.
- the individual packet error 26 is initially accepted.
- the likelihood of recurrence of a packet error 26 is reduced due to the stronger channel coding using packets 210 .
- the signaling 211 B of the first packet error 26 can still take place in the first cycle.
- the additional delay until the following error-free data packet is received is only extended by the transmission of the additional redundancy and the somewhat more complex error correction. This delay is still tolerable by most real-time systems, however, and is much lower than in a method in which it is attempted to retrospectively correct the packet error 26 that has already occurred, without the need to send the entire data packet 21 , 210 again. This is because such a packet is only available at the receiver error-free after a delay, which results from the error signaling, transmission of the additional redundancy and performing the error correction. Such a long delay is often not compatible with time-critical real-time systems.
- the receiver can receive the correct signal 211 A, 211 B error-free in each case. If an ACK signal 211 A is misinterpreted as a NACK signal 211 B, then the transmission of non-time-critical data 213 will be unnecessarily interrupted in order to apply a stronger channel decoding. This reduces the effective user data rate for the non-time-critical data 213 more than necessary. If, on the other hand, a NACK signal 211 A is misunderstood as an ACK signal 211 A, then despite a first transmission error, the channel coding is not strengthened. The likelihood of critical multiple errors is thereby greatly increased.
- the two pieces of information are optionally secured by a separate strong channel coding, which is independent of the channel coding 200 of the user data 212 and/or 213 and also has an extremely low error probability. Since here only two bits need to be protected, such a permanent, stronger channel coding would be acceptable.
- the two pieces of information could be included in the signaling data 211 .
- control device 10 has the absolute control over the transmission via the transmission medium 20 .
- a deterministic behavior applies. Such behavior is standard practice for a network with a central controller as the control device 10 and is common practice in many industrial networks.
- the central controller as control device 10 has sole control over the time-critical resource allocation and the data formats used.
- the slaves or the other components 31 , 32 , 33 can autonomously access the channel of the transmission medium 20 .
- a slave cannot assume it will obtain sole access here.
- the sole control over the data format of the time-critical data 212 is also present in the present method, even if the component 31 in the example of FIG. 5 instructs the control device 10 as a central controller with the NACK signal 211 B to change the packet structure in the next cycle. It is conceivable though, for the control device 10 as a central controller to retain the final control over the packet types used, if this seems to make sense for specific reasons. Thus, the control device 10 as the central controller could ignore NACK-signals 211 B in the forward direction and continue to use the weaker channel coding. This makes sense, for example, if no other time-critical data 213 are available for transmission. On the other hand, the control device 10 as the central controller could also use a stronger channel coding 200 in the forward direction, despite an ACK-signal 211 A in the reverse direction.
- the channel coding 200 in the reverse direction could be controlled by the control device 10 as the central controller by signaling 211 A, 211 B of ACK and NACK, regardless of whether the preceding decoding was successful or not.
- the components 31 , 32 , 33 should not deviate from the standard procedure. Thus, they should always apply the channel coding 200 according to the signaling and report detected errors uncorrupted to the control device 10 as the central controller.
- a third exemplary embodiment is based on the assumption that a minimum of two or more packet errors 26 are critical for the correct operation of the industrial plant 1 .
- the procedure taken is as follows.
- the stronger channel coding is only used if M ⁇ 1 consecutive packet errors 26 have already occurred. This also results in more lead time for the network devices 10 , 31 , 32 , 33 for changing the channel coding.
- the stronger channel coding even the first packet error leads to a system failure.
- the stronger channel coding is used when fewer than M ⁇ 1 consecutive packet errors 26 have occurred. This only leads to a system failure if more than one packet error 26 occurs with stronger channel coding. This probability is significantly lower.
- a fifth exemplary embodiment for the case in which only M>3 consecutive packet errors 26 are system critical, up to M ⁇ 1 different strengths of channel coding are provided and the channel coding 200 is increased for each additional consecutive packet error 26 .
- the industrial plant 1 can be a programmable logic controller (PLC).
- the industrial plant 1 can be a CNC controller (Computerized Numerical Control).
- the industrial plant 1 can be or have a movement logic controller, for example for transport systems or for guiding tools, etc.
- the previously described method may be used in any desired configurations or systems, in which data must be transmitted in a time-critical way, but isolated packet errors are not critical.
- the approach described is particularly interesting for real-time communication in industrial automation. But any other real-time data stream is conceivable, in which individual packet errors can still be corrected by interpolation, but multiple errors are to be prevented.
- Other examples can be control tasks in vehicles (steer-by-wire, brake-by-wire), where it is more important in the event of an error that current commands are transmitted successfully, than that previous commands are repeated.
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